INCREASED BASIC FIBROBLAST GROWTH-FACTOR MESSENGER-RNA FOLLOWING CONTUSIVE SPINAL-CORD INJURY

Neurotrophic factors appear to be crucial for the survival and potenti al regeneration of injured neurons. Injury of the peripheral nervous s ystem results in the induction of a number of neurotrophic molecules. Less is known about the response of central nervous tissue to injury. We have examined changes in levels of mRNA for three trophic factors, basic and acidic fibroblast growth factor (bFGF, aFGF), and nerve grow th factor (NGF), after a standardized incomplete thoracic contusive sp inal cord injury (SCI). RNase protection assays showed a rapid increas e (3-fold) in the content of bFGF mRNA by 6 hours after SCI in tissue that included the injury site. No effect of injury was seen in segment s of cervical or lumbar cord. bFGF mRNA at the injury site remained si gnificantly increased at 1 and 7 days after SCI. Further, at 7 days, t he increase was anatomically restricted to the rostral portion of the injury site suggesting the involvement of specific pathways in the mai ntenance of high levels of bFGF mRNA. No change in the levels of aFGF mRNA was seen after SCI. Similarly, no difference in the expression of the mRNA for NGF or its high affinity receptor (trkA), were observed at 6 h, 1 or 7 days following SCI. Our observation of a specific effec t of SCI on bFGF mRNA expression supports a speculative hypothesis tha t bFGF may play a role in the partial recovery of function seen follow ing incomplete contusive spinal cord injury.